46 BC12D Compass

[Hank Jarrett]

There are actually two different versions of the bubble face. One with a square window (left) and one with a round one. I put the round one in the 41 and the square one will go in the 45. The single compass photo is the 41 compass as received back from Keystone.





41 T Compass2.JPG2 Bubble face compass front 1.JPG

[M Towsley]

Jim,

I was advised a non-lit B16. I found one non-lighted, as many of them come with the light from WWII electric aircraft. Not that easy to find and usually need repairs, like mine. My understanding is lack of parts like the diaphragm, which mine needs. I need to call around and find a place that has parts and can restore mine.

Marty

[Jim Herpst]

Marty,

Well thank you for the ID of the part! Now crap yet another part that ihas been made obsolete . One would think as a surplus WWII part it would have had a pretty large following. Hence parts to fix it.

Do you have the exact part number ? Or is simply non electrical B16?

Best,
Jim

[M Towsley]

Jim,

As far as I know just a non-lit B16 compass. I will go look at it and see if there is a specific part number for the compass. Ryan Newell is the one who put me onto it when I finally found the 'correct' mount. Stand by...

Marty

[M Towsley]

Jim,

An Airpath is all I can see. The remnants of some type of sticker is present but no data, been rubbed off over the years.

Marty

[Jim Herpst]

Jim,

An Airpath is all I can see. The remnants of some type of sticker is present but no data, been rubbed off over the years.

Marty

Thank you Marty. If you could also post a picture with a side and rear view I would much appreciate it. I do see a couple of B16 for sale on E bay but they are not the same me thinks anyway. Have you called Keystone for the ability to OH yours?

[astjp2]

I adapter an airpath from spruce, looked like the aluminum casting but easy to fit.

[Jim Herpst]

Is it one that mounts up in the windshield. I am not doing a panel mount and I do have the bracket that bolts up to the frame.

[M Towsley]

Jim, sorry, I did not check back here until today. Hopefully I can remember to take a couple of pics tomorrow. I have not called Keystone, yet. I have their phone number right next to my chair but it got buried under books/magazines.

[Jim Herpst]

Thanks Marty. No sense chasing down the orginal if one cannot be repaired. I did notice the one I have is an Airpath albeit the new style now offered by ASS. Since I also have the orginal bracket it can fit that with a simple horizontal piece of metal added to mount the new housing that is smaller to it. It certainly is lighter than the original and some may say not so clunky looking.. but not orginal either. Wish the46 had used the fishbowl compasses of prewar vintage.They sure were a nice piece.! Any way thank you again Marty for checking.

[M Towsley]

Jim,

Hope these help. I will try to call Keystone next week. FYI screws holding on the front are out of the unit so those are not showing.

Marty

[Jim Herpst]

That is the same as what was on 43831for sure! Well next lest see if it is doable to get one working today. THANK YOU

[Scott]

In 46, according to the factory drawings, the "Optional" compass mount is Screenshot_20210314-001405_Drive.jpg on top of the instrument panel. Mounting the compass in this location means it will actually work.

I'd be interested to hear if anyone has actually managed to compensate a cross-tube mounted compass to read withing 5 degrees of each of the cardinal headings.

When I tried my compass in the cross-tube location it was over 60 degrees off. I I didn't bother to swing it as there's no compensating for that.

Mounting a compass to steal structure runs counter to everything we know about magnetic compasses. If it ever worked, it couldn't last long, any change in local conditions, a thunderstorm perhaps, or pirate radio station will change the field around the steal tubes.

Anyway I understand the nostalgia of the tube mounted compass, but the glareshield mount is in fact just as original for the BC12D.

[woodmw]

Mooney mounts the compass on the structural steel tube that runs down the wind screen. My C-model had a problem compensating the compass to the South until I went to Dugosh Aircraft in Kerrville for the voodoo of degaussing. While watching the process, I was expecting a High Princess to start dancing around the plane with bells and incense. But it worked.

[Hank Jarrett]

Degaussing works fine. We did whole ships to keep them from setting off magnetic mines. Sometimes it even worked (on the ships). Never had problems with my big compass (yet).

Hank